fixed relayouting of GenericParameterPage

refs #641

Change-Id: Ie442cc8822f5a8709e2865071c88fa87cd93c405
Reviewed-on: http://gerrit.esdi-community.eu/3141
Tested-by: Jenkins <sitemple@igd.fraunhofer.de>
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>